Wednesday, October 5, 2011

Digestive System

I've got my 3.75 year old twins at home instead of in preschool for a short period of time, this is Day 3 of my Big Preschool at Home project- I'm hoping to keep up with the blogging, both as a record and to help anyone else who is planning something similar or wants to supplement preschool with some discovery learning and science activities.

The digestive system day got off to a rocky start with both kids cranky- my more resilient kid was brought to tears because her brother was the first to find a pen for our shopping list!

I've been so focused on our body lessons that I haven't quite stayed on top of some household duties, so we started by first talking about food in our house, food that is healthy, and what different foods help our bodies do. Anya has been toying with the idea of not eating anything that comes from dead animals- her love of sausage and bacon is proving a sticking point for any vegetarianism- and so we talked a lot about the sources of different types of foods. That segued nicely into getting a household chore done: the shopping list and trip to the grocery store.

Our usual method is that I ask each kid to list 2-3 things they think we need, and as they say them I first draw a picture of the item, then sound out the word as I write it out. Each kid gets a list made this way, and it is their job to keep an eye out for their items and remind me to get them. I'm always pleased when they can remember something beyond their favorite foods and especially when they ask what ingredients we need to make something they are craving for dinner, I hope it is a skill that comes in handy when they are on their own- I know plenty of adults who have a hard time shopping effectively and planning meals!

During our drive to the store I talked them through the process of digestion. I asked them to tell me what happens first to food that we eat, and was expecting to hear "it goes to our tummy", and so I was thrilled when Anya told me that first our teeth "crunch up all our food"- that led into talking about saliva and how it and the teeth start the process and help make the food into a moist, soft ball to swallow. I also threw in a little bit about the importance of chewing and had them think about times that they had swallowed something hard and had it hurt- tortilla chips being the big offender. We talked about the stomach and how it mechanically squishes the food up even more, and I introduced the idea of stomach acid that continues to break down and soften the food even more. The intestines are next, and I was able to tie them into the circulation system we talked about yesterday. I made sure to ask some questions to prompt them to remember yesterday's lesson, and it definitely helped. Then we talked about how the nutrients and good stuff were transferred from the food in the intestine to the blood waiting to take the nutrients to the hungry cells. And then, once all the good stuff is taken out, the waste that's left over is... POOP! Oh, so much joy in our household! Learning about POOP!

As a side note, I use driving time to introduce topics and do my little mini-lectures a lot because

Anya's Macrophage

It staves off boredom in the car, and as any Yoda Mama knows, boredom leads to antsy-ness, antsy-ness leads to button-pushing, button-pushing leads to fighting and fighting leads to yelling, misery and the Dark Side.

I have a captive audience, and the kids are much less likely to get distracted by the cat walking by or a beloved toy in the corner or a shiny piece of tinfoil on the floor. It doesn't take much with the three year old set!

They love it! Seriously, they get excited and request certain topics over and over. I credit our driving talks about the immune system for the fact that Anya drew that thing on the left. When I asked what it was she said, "It's that kind of tiny cell in your body that eats all the bad germs, what's that one called again? Yeah, a macrophage, it's a macrophage!" My heart, she swoons!

Later, we did our big digestive system project:

First we got a couple of ziploc bags, a small container of water dyed green, a little bit of vinegar, some saltines, a cheap nylon knee-high (left-over from making fairy wings, you can pick 'em up 4/$1 and they have tons of uses, grab some next time you see 'em for cheap!), scissors and a Sharpie.

I talked to them about digestive acid in the stomach again, and showed them how I added some vinegar to the green water to make our pretend stomach acid. Then I had them help spell their own names on the bags and drew a simple drawing of the stomach, along with arrows showing where food goes in at the top and out into the intestines at the bottom. We added our stomach acid and then the kids started adding crackers. Once the bags were sealed, I asked the kids to be the stomachs, to mush the crackers up so that our pretend body could digest them.

They went to town, and I had them stop and make observations about the changes in the crackers, "like playdough" and "soft" were the two big descriptors. It think it is one of the coolest meta-learning parts of projects like this, that they are learning the scientific method, from lit review to gathering materials to performing the actual experiment to observing the subject and finally talking about the whole experience and learning to apply it to other situations. I'm hoping to introduce ultra simple hypothesis testing soon, and getting them used to the idea by frequently asking them questions in the form of "What do you think will happen when we do ______?"

I let them play with the stomachs for a while while I cleaned up. I've found it is really important for them to have plenty of breaks from active talking and lessons, though I admit that my tendency is to go on and on. I kind of wish I had had this experience with preschoolers before I taught experimental methodology to undergrads- I would have been a better teacher if I had learned that not everyone wants to be overloaded and stuffed full of info while in learning mode! It's also important for me to take these breaks, so that the mess of two kids at home doesn't start overwhelming my already-scant housekeeping skills and so that I have some recharge time to avoid feeling spread too thin.

Next up, intestines! I took the stocking and cut off the toe, and used the empty water cup to hold it open, cut the corner off the ziplocks and had the kids help me squeeze the stomach contents into the intestines.

I showed the kids how the lining of the intestines was permeable- it lets some oozy stuff out which I called the nutrients- and I explained that the blood vessels came right up next to the intestines and let the blood pick up food for all the hungry cells. As we squeezed more of the mush through the nylon, more of it came out the sides as nutrients, and the stuff in the middle got smaller. I asked them which was bigger, all the food we eat in a day piled together or the poop we have the following day, and pointed out that that's because our body takes in and keeps all the good stuff and pushes the rest out as poop. The grand finale, of course, was when the nylon finally pooped out the leftover green-cracker-mush-pretend-poop. Messy but totally worth it!